Explosionproof fitting for electric glowlamps



J. BECKMANH May 17, 1927.

EXPLOSIONPROOF FITTING FOR ELECTKIC GLOW LAMPS Filed Nov.

int/77 of" J i, detail thereof on a Patented May 17, 1927.

UNITED STATES PATENT OFFICE.

' aormiwns BECKMANN, or amona-o'rrnnsnn, emmmmr.

EXPLOSIONPBOOF FITTING FOR ELECTRIC GLOWLAMPS.

I Application filed November 30, 1926, Seria1 No-.151,792, and in-Germany March 3, 1926.

This invention relates to an explosion proof fitting for electric glow-lamps, and more particularly to an improved safetyswitch for the same which prevents the 5' glow-lamp being switched-on with open fit- 'tingand thus avoids any formation of dangerous sparks, while it allows a switchingon of the glow-lampin the closed position of the fitting only.

1o The accompanying drawing illustrates the improvement: Figs. 1 and -2 are longitudinal sections through the explosionproof fitting with the glow-lamp, in its closed and open position respectively; Figs. 3 and 4 show a arger scale, in the closed and open position of the fitting respectively;

Fig. 5 is a section on the line l-1 of Fig. 1 on a larger scale.

A non-turnable slide 1 is arranged 'in a casing 2 of the stationary member 3 of the fitting'and acted upon by a pressure-spring 4. Said slide is slotted at5 and there-adapted, in the open position of the fitting, to

straddle, by action ofthe spring 4, a flattened member 6 of 'a'switch axle thereby locking the latter against turning and thus preventing a switching-on of the glow-lamp 7 in the open position of the hinged member.

8 of the fitting. The latter is pivoted at its rear end 13 and llasat-its front end a lug 11 with an open-ended key-hole 9, 10 therein, which when closing the fitting and in the closed. position thereof retracts the slide 1 against the action ofthe spring 4 and enters the open end of the casing 2 so far that the flattened part 6 of the switchaxle is located within the round vboring 10 of the keyhole 9, 10 and can then be freely turned therein, thereby allowing a switching-on of ary fitting member, a spring-influenced nonthe glow-lamp in the closed position of the 4 fitting only. Besides, the switched-on position of the flattened part 6 of the switch axle (Fig. 1) prevents an opening-of thefitting even after loosening of the fastening-screws 12 thereof as long as the glow-lamp is alight. The latter must first be switched-ofi by turning the switch axle so that'its flattened part turnable slide in said casing having a slotted end and adapted to straddle therewith the flattened switch axle part and thus to prevent. a turning thereof in the open positionof the hinged fitting member, alug on the hinged fitting member having an open-ended keyhole therein and adapted to enter the open end of the casing and to retract said slide while receiving the flattened switch axle part in the round boring of itS'kyl'lOle and allowing a turning thereof in its closed position only, said flattened switch axle part in its switched-on position preventing, an opening .of the hinged fitting member even after loosening of said fastening-screws.

In testimony whereof I have hereunto set m hand.

y JOHANNES BECKMANN; 

